SATUN Aspiring Geopark
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INTERNATIONAL GEOLOGICAL SIGNIFICANCE SATUN Aspiring Geopark TABLE OF CONTENTS Abstract………………………………………………………………………………………........... 1 A-International Geological Significance..…………………………………………………….......... 1 A-1. Tarutao Island Type Section……….......................................................................................... 1 A-1.1 TaruTao Group………………………………………………………………............. 1 A-2. Khao Noi Type Locality………………………………………………………………………. 3 A-2.1 Thung Song Group (Ordovician) …………………………………………………… 3 A-2.2 Thong Pha Phum Group (Silurian-Devonian-Carboniferous)………………………. 4 A-3 Kaeng Krachan Group (Uppermost Carboniferous-Lower Permian)…………………………. 4 Annex Annex 1 Stratigraphic Type Section, Tarutao Island…………………………………………......... 5 Annex 2 Khao Noi Stratigraphic Type Area………………………………………………….......... 10 Annex 3 Kaeng Krachan Group……………………………………………………………………. 21 REFFERENCES……………………………………………………………………………………. 22 1 International Geological Significance Abstract In terms of geological setting, Satun Aspiring Geopark and Langkawi UNESCO Global Geopark are on the same tectonic plate setting which was a part of Gondwana having moved from the Southern Hemisphere to form a part of Shan-Thai plate as seen in the present time. Both of them possess a complete Paleozoic geological succession ranging from Cambrian to Permian. Type sections and type localities have been studied and designated to both areas. Some limestone units of both geoparks have formed an outstanding feature of spectacular beautiful karst morphology. The geological international significant can be classified into 4 categorizes. 1) The Tarutao Group type stratigraphic section at the Tarutao Island, where many Cambrian-Ordovician index fossils and new genus are found. Furthermore, brachiopod and conodont fossils identified Cambrian-Ordovician boundary. Recently, absolute dating of ash layers found between the index fossil layers at the Cambrian- Ordovician boundary has been studied and this may bring to another indication of absolute age of the Global Boundary Stratotype Section and Points (GSSP). 2) The stratigraphic type locality at Khao Noi and the stromatolitic limestone aged Ordovician-Devonian. 3) Biostratigraphy and biodiversity where every period of the Paleozoic Era is delineated by fossils and/or index fossils. 4) Depositional environment of the Kaeng Krachan Group was involved glaciomarine mass flow origin as indicated by Bouma sequence and drop stone. A-International Geological Significance Geosites designate as International Geological Significance mentioned in the application dossier will be described more detail as follow. A-1 Tarutao Island Type Section A-1.1 Tarutao Group: The Tarutao Group was named by Javanaphet (1969) for red sandstone, slate and quartzite in southern Thailand. The type section situated at western part of the Tarutao Island, Satun province. Presently, the Tarutao Group was refer to all of sandstone and quartzite sequences in Thailand that underlying the carbonate Thung Song Group (Fig. 1). The Tarutao Group has more than 1,000 m in thickness. It comprises interbedded of thin to thick bedded, sandstone and red shale. Tabular cross bedding was found at upper part of the sequence, reveals eastward paleocurrent flow (Bunopas, 1981; and Teraoka et al., 1982). Fossil assemblages in the formation indicate the age of the rocks to be Late Cambrian to Early Ordovician (Kobayashi, 1957; and Shergold et al., 1988: Stait et al., 1984). Good exposures of upper part of the Tarutao Group located at Malaka bay, northern shores of the Malaka river mouth, northwest of Tarutao island and at southern side of Ao Tal Dang (Wongwanich et al., 1983). Bunopas (1981) described the rocks of the Tarutao Group at a type section in the area of Talo Topo bay (now called Ao Mo Lae). Sequence of rock succession is at the middle to upper part of Tarutao Group with 700 m in thickness. Details of the Tarutao Group at Talo Topo bay (Ao Mo Lae) and lower part at Ao Dan are listed. Upper part: Thin to medium beds of brown to grayish brown sandstone, interbedded with siltstone and shale, unseen upper part Thickness; 300 m 2 Middle part: Medium beds of brown to brownish pink sandstone, thin shale interbedded Thickness; 180 m Thick to very thick beds of cross bedded brown quartzitic or orthoquartzite, gray to green shale interbedded Thickness; less than 270 m Lower part: Thick beds of brown to grayish brown, coarse-grained sandstone with inclusion of some conglomerate and ilmenite mineral. Thickness; less than 100 m Figure 1 Geologic map of the Tarutao Island (Clive and Chaodamrong, 2017, personnel communication). 3 Numerous trilobites and brachiopods are present in the west of Tarutao island. Kobayashi (1957) dated a common trilobite fauna yield the Late Cambrian. The best known trilobites are Pagodia thaiensis, “Eosaukia” buravasi, and Coreanocephalus phanulatus while brachiopods are Apheorthis (?) sp. Shergold et al. (1988) studied the trilobites of the Tarutao Group from Tarutao island and concluded that they are Late Cambrian to the boundary between Cambrian and Ordovician. The oldest trilobites are found in the west of Tarutao island and west of Laem Hin Ngam and include Hoytaspis? thanisi, and Prosaukia ? aff. nema. The younger trilobite fossils were found in Talo Topo bay consisting of Lichengia? tarutaoensis (Kobayashi) (= Saukiella tarutaoensis), Lophosaukia cf. sp. indet., Quadratichephalus planulatus Kobayashi (= Coreanochephalus planulatus), Leiostegiid gen. et sp. indet., Shumardiid gen. et sp. indet., Szechuanella ? cf damujingensis, Thailandium solum, Tsinania (Tsinania) cf. jiangnanensis, Micragnostus (Micragnostus) nomas. The trilobite assemblage is closely related to those previously described from the inner detrital environments (rather than platform carbonate) of northern Vietnam, western Yunnan, Sichuan, Gansu and eastern Qinghai and in central Australia (Shergold et al., 1988) and may indicate proximity of these areas in the Late Cambrian to Early Ordovician (Burrett et al., 1990). The youngest Cambrian fossils were found at Talo Udang bay as identified by trilobite; Parakoldinioidia thaiensis, (= Pagodia thaiensis), which dates closely to the Cambro- Ordovician boundary. Ordovician fossils are limited to the uppermost part of the Tarutao Group at Malaka bay, northwest of Tarutao island (Wongwanich et al., 1983) and Talo Udang bay in south of Tarutao island (Stait et al., 1984). The fossil strata are the Pagodia- Eosaukia fauna beds described by Kobayashi (1957). This Middle to Upper Tremadoc fauna consists of Pseudokainella malakensis, Asaphellus sp., Geragnostus, Rossaspis bunopasi and a harpid. Rossaspis also occurs in the overlying Thung Song limestone on Tarutao island and in Kanchanaburi province (Wolfart 2001). In conclusion, Upper Cambrian of 19 species of trilobites were described by world expert (John Shergold) with stratigraphic and sedimentological control. Furthermore, brachiopod and conodont fossils identified Cambrian-Ordovician boundary. Recently, absolute dating of ash layers found between index fossil layers at the Cambrian-Ordovician boundary has been studied and this may bring to another indication of absolute age of the Global Boundary Stratotype Section and Points (GSSP). Lower Ordovician trilobite fauna on the Tarutao Island indicates succession of highly fossiliferous limestone. Detailed studied on sedimentology discloses that the layers contains nautiloids*, conodonts*, the gastropod Peelerophon oehlerti (Gondwana)* and chiton Chelodes whitehousei (Australia) * and brachiopods Syntrophina & Archaeorthis?. In Satun mainland, similar faunas to Langkawi. Spanodonta – Australian brachiopod and Aportophyla* and nautiloids*. Characteristics of lithology and fossils of the Tarutao Group in Tarutao island are illustrated in annex 1. A-2 Khao Noi Type Locality A-2.1 Thung Song Group (Ordovician) Thung Song Group was firstly called Thung Song limestone by Brown et al. (1951). It was upgraded to the Thung Song Group by Javanaphet (1969). Later, Burton (1974) called Ordovician limestone in Nakhon Si Thammarat (Thung Song district) that lying over the Cambrian sandstone and quartzite as Nai Tak formation. Bunopas (1981) named this group of rocks found in Tarutao island as Thung Song formation. Recently, most of geologists names Ordovician limestone in the south and other regions in Thailand as the Thung Song Group. Characteristics of rocks and fossils in the Thung Song Group by Wongwanich (1990) at the tarutao island and are described in annex 2. 4 Bunopas (1981) reported the continuation of the rock sequence in this group was found in eastern end of Talo Udang bay, south of Tarutao island. Lower to middle part and gradational contact between the Thung Song Group and underlying red sandstone of the Tarutao Group were found. The upper part of the group is exposed at a limestone mountain in northeastern part of the island close to Rusi bay. Detailed study of the Thung Song Group at Tarutao island has been made by Teraoka et al. (1982), Wongwanich et al. (1983), and Wongwanich (1990). The study of the Thung Song Group at Tarutao island can be divided rocks into 6 formations. Sequence of rocks conformably lies over the red sandstone of the Tarutao Group. In addition, Wongwanich et al., (1990) found the uppermost part of the Thung Song Group in area north of La-ngu district, Satun province, consists of another formation of red deep marine limestone. In conclusion on fossil biodiversity, Middle Ordovician comprises large, well preserved, fauna